Three Digit Up Down Counter Circuit

We are offering  Three Digit Up down Counter Circuit  enables users to count from 0 to 999 in up as well as down mode at any instant of counting. three digit updown counter can be used for many applications such as clock generator, frequency meters etc.

The circuit uses three updown counter ic1, ic2 & ic3 and three bcd to seven segment decoder ic4, ic5 & ic6. The clock’ circuit and updown switching are designed using nor gate as ic5. Three 7-segment displays in common cathode configuration are used to display the count.

About the circuit :
When power is switched on, the clock pulses generated by rc network build around two nor gates in ic5 is fed to the clock input (pin1) of ic1, ic2 & ic3. As a result counting starts in up or down mode depending on the logic present at updown mode pin10. If pin10 is at high level, counter starts up counting and starts down counting when it is at low level. This logic is set with the aid of logic circuit design using two nor gates in ic5 and toggle switch s1. When s1 is in up position, pin10 gives logic high and when s1 is in down position, it gives logic low. Reset switch s2 is used to reset the counter. In this case, displays show 000 in two 7- segment displays and counting starts again.

At every clock pulse, count increases by one in up mode and decreases by one in down mode. The clock-out terminal (pin 7) of ic1 is connected to clock-in terminal (pin 5) of ic2. Similarly, clock-in terminal of ic2 is connected to the clock-out terminal of ic3. Thus, when ic1 completes counting from 0 to 9 in up mode or 9 to 0 in down mode, ic2 starts counting. In the similar way, ic3 counts. The display can be shown on three 7- segment displays named as dis1, dis2 and dis3.

The speed of counting can be set with the aid of pot p1. The number of digits the counter provides can be extended by adding more counterdecoderdisplay stages.